Summary Of DNA Bender: Cren7 And Sul7
DNA bender: Cren7 & Sul7
DNA benders can introduce a bend in the DNA (Luijsterburg et al., 2008). Many bends in the DNA automatically provide compaction of the DNA. Two important DNA bending proteins in crenarchaea are Cren7 and Sul7 (Driessen et al., 2013). They are similar in structure, but they have different DNA binding regions (Zhang et al., 2015). Cren7 and Sul7 can be methylated at several lysine residues (Guo, 2007). This PTM might be to regulate gene expression (Feng et al., 2010), although the methylation does not alter the DNA-binding affinity of these proteins. It is not clear whether and how these modifications alter the function of Cren7 or Sul7 (Driessen & Dame, 2013).
Tethered particle motion (TPM) experiments can be performed …show more content…
Single-molecule techniques used to study architectural proteins. A. Magnetic tweezers (MT). A DNA molecule is attached to a paramagnetic bead. The bead is trapped in a magnetic field. The magnetic field can be twisted and rotated so that MT can also be used for micromanipulation of the protein-DNA complex. The diagram shows a force extension curve for bare DNA (black) and for DNA bound to Cren7 (red). This shows that Cren7 reduces the extension of DNA. B. Optical tweezers (OT). A DNA molecule is on two sides attached to a bead. The beads are trapped in a mobile optical trap. The beads can be moved and force can be applied on the DNA molecule. A force extension curve is shown of bare DNA (black) and DNA bound to Alba (red). The peaks show the disruptions of loops formed. C. Tethered particle motion (TPM). A DNA molecule is attached to a bead. The movement of the DNA molecule can be studied. The possible positions of bare DNA are shown (black) and of DNA bound to Cren7 (red). This shows that DNA bound to Cren7 is more compact than bare DNA. D. Atomic force microscopy (AFM). A DNA molecule or a protein-DNA complex is put on a flat mica surface. The surface can be scanned with a small tip of the AFM. The surface can be visualized on a nanometer scale. An image of bare DNA (top) and DNA bound to Alba1 (bottom) are shown. These pictures show that Aba1 forms bridges on the DNA. (Driessen, 2014: …show more content…
In crenarchaea there are only a few DNA wrapping proteins, such as Lrp (Leucine responsive regulatory protein). It forms octameric structures with multiple binding sites that wrap the DNA around itself (Luijsterburg et al., 2008). This causes positive supercoiling and it promotes DNA compaction.
DNA wrappers can be studied with magnetic tweezers (MT). The DNA molecule is attached at one end to a paramagnetic bead and to the glass surface on the other end. The bead is trapped in a magnetic field. The conformational changes in the DNA molecule can be observed if DNA bending proteins are added (see Figure 1A). Also manipulations can be performed with OT. The magnetic field can be twisted or moved perpendicular to the surface to change the extension in the DNA and to apply forces on it (Dame, 2008).
Conclusion and future
DNA benders can introduce a bend in the DNA (Luijsterburg et al., 2008). Many bends in the DNA automatically provide compaction of the DNA. Two important DNA bending proteins in crenarchaea are Cren7 and Sul7 (Driessen et al., 2013). They are similar in structure, but they have different DNA binding regions (Zhang et al., 2015). Cren7 and Sul7 can be methylated at several lysine residues (Guo, 2007). This PTM might be to regulate gene expression (Feng et al., 2010), although the methylation does not alter the DNA-binding affinity of these proteins. It is not clear whether and how these modifications alter the function of Cren7 or Sul7 (Driessen & Dame, 2013).
Tethered particle motion (TPM) experiments can be performed …show more content…
Single-molecule techniques used to study architectural proteins. A. Magnetic tweezers (MT). A DNA molecule is attached to a paramagnetic bead. The bead is trapped in a magnetic field. The magnetic field can be twisted and rotated so that MT can also be used for micromanipulation of the protein-DNA complex. The diagram shows a force extension curve for bare DNA (black) and for DNA bound to Cren7 (red). This shows that Cren7 reduces the extension of DNA. B. Optical tweezers (OT). A DNA molecule is on two sides attached to a bead. The beads are trapped in a mobile optical trap. The beads can be moved and force can be applied on the DNA molecule. A force extension curve is shown of bare DNA (black) and DNA bound to Alba (red). The peaks show the disruptions of loops formed. C. Tethered particle motion (TPM). A DNA molecule is attached to a bead. The movement of the DNA molecule can be studied. The possible positions of bare DNA are shown (black) and of DNA bound to Cren7 (red). This shows that DNA bound to Cren7 is more compact than bare DNA. D. Atomic force microscopy (AFM). A DNA molecule or a protein-DNA complex is put on a flat mica surface. The surface can be scanned with a small tip of the AFM. The surface can be visualized on a nanometer scale. An image of bare DNA (top) and DNA bound to Alba1 (bottom) are shown. These pictures show that Aba1 forms bridges on the DNA. (Driessen, 2014: …show more content…
In crenarchaea there are only a few DNA wrapping proteins, such as Lrp (Leucine responsive regulatory protein). It forms octameric structures with multiple binding sites that wrap the DNA around itself (Luijsterburg et al., 2008). This causes positive supercoiling and it promotes DNA compaction.
DNA wrappers can be studied with magnetic tweezers (MT). The DNA molecule is attached at one end to a paramagnetic bead and to the glass surface on the other end. The bead is trapped in a magnetic field. The conformational changes in the DNA molecule can be observed if DNA bending proteins are added (see Figure 1A). Also manipulations can be performed with OT. The magnetic field can be twisted or moved perpendicular to the surface to change the extension in the DNA and to apply forces on it (Dame, 2008).
Conclusion and future